Microarray systems may be used to detect and quantify biomolecules such as antibodies, antigens, oligonucleotides, and RNA for a variety of clinical purposes such as understanding gene expression, gene regulation, protein production, protein modification, etc. Biomolecules may be adhered to microarray spots or wells formed on a glass slide or chip, and a fluorescent label, such as an organic dye, may be bound to a target subset of the biomolecules. Light from a laser may be directed to the biomolecules, and those biomolecules tagged with the fluorescent label may emit light in response to excitation from the laser. In some examples, light emitted from the luminescent labels may be gathered by a lens system and an image of the illuminated biomolecules may be captured. The image may then be analyzed to quantify expressions levels of the target biomolecules. Specifically, the intensity of different wavelengths of light may be compared to determine the relative intensity of emissions at wavelengths associated with the fluorescent tags. Because the fluorescent tags are bound to the target biomolecules, biomolecule expression levels or concentrations in the samples being tested, may be inferred based on intensity levels of light produced by the fluorescent labels.
In one example, microarrays may be configured to measure protein levels. Specifically, protein microarrays may be configured to measure antibody levels in a sample (e.g., lysate, serological, blood, or synthetic samples). As such, protein microarrays may be used to identify and/or diagnose infectious diseases. Proteins (e.g., antigens) may be affixed to a nitrocellulose film coating on the chip. When incubated with patient samples (e.g., whole blood, serum, plasma, saliva) containing antibodies specific to the printed antigens, the antibodies may bind to the antigens on the array. Probe molecules tagged with the fluorescent label may then bind to the antibodies, illuminating the antibodies when exposed to the laser beam. A clinical diagnosis may be made based on antibody expression levels as inferred from the luminescence, and therefore concentration, of the fluorescent labels.
However, the inventors herein have recognized potential issues with current microarray systems. As one example, image acquisition in most microarray systems is accomplished by a laser scanner included in the microarray system. Laser scanners may be necessary to deliver images at high enough resolution qualities to make accurate biomolecule identification and quantification determinations. However, laser scanners are often very large, and as a result current microarray system are stationary and not transportable. Further, many microarray systems may include multiple laser scanners for wavelength multiplexing, increasing the size, weight, and expense of such microarray systems. Thus, samples including the biomolecules must be taken to the microarray and scanner for analysis. As such, it may take a significant amount of time to render a diagnosis due to the delay associated with transporting the sample from a patient to the microarray scanner.
In another example, diagnosis determination may be difficult due to the low sensitivity of the protein microarrays. Specifically, organic dyes used to fluorescently label the biomolecules may have relatively broad emission and absorption bands, resulting in increased amounts of background noise in the biomolecule images. Additionally, light emitted from the organic dyes may be of low intensity. Further, the dyes may be prone to optical fading (photo bleaching) after exposure to intense excitation light. As such, image resolution may be low, and differentiation and quantification of the biomolecules may be challenging, resulting in reduced accuracy of disease diagnoses in protein microarrays.
In one example, the issues described above may be addressed by a microarray assembly comprising a laser emitting in a first direction, a camera positioned parallel to and vertically below the laser, a first dichroic mirror horizontally aligned with the laser for reflecting light emitted from the laser, a second mirror horizontally aligned with the camera and vertically aligned with the first dichroic mirror, and a chip coated in a nitrocellulose film and including an array of wells containing one or more biomolecules. In this way, the size of the microarray may be reduced by utilizing a camera instead of a laser scanner for acquiring an image of the wells. The size may be further reduced by positioning the camera and laser in parallel with one another, thereby increasing the portability of the microarray.
In some examples, the assembly may further include a cuvette for housing the chip, the cuvette including one or more of an aperture and groove for receiving the chip. The cuvette may additionally include an optically clear window integrally forming a front wall of the cuvette. The front wall of the cuvette may be pointed towards the first dichroic mirror for receiving a light beam produced from the laser. By including the cuvette for the chip, instances of contamination may be reduced.
In other examples, the biomolecules may be tagged with a fluorescent label, where the fluorescent label may comprise Quantum Nanocrystal fluorescent-nanoparticles (QNC). By using QNC to label the biomolecules as opposed to organic dyes, the sensitivity and resolution of the images captured by the microarray may be increased, allowing for improved accuracy in the diagnosis of infectious diseases.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.